Robert Smolenski

Common mode current paths and their modeling in PWM inverter-fed drives

This paper investigates the paths of common mode currents in a PWM drive system. On the grounds of experimental results, a high frequency model of this system has been established. Separate analysis of the drive components and their contributions to common mode current flows have been done. On this basis, the authors have ascertained that heat sink-to-DC link capacitance is essential for creating the grounding currents paths. The large value of this capacitance constrains the CM currents to flow on a motor side of the system and reduces the conducted emissions measured on a supply side of the inverter (e.g. by means of LISN). In the case of a small value of heat sink-to-DC link capacitance a larger part of the CM currents can flow via mains, and the inductance of this path contributes to a creation of a low frequency part of the CM currents. In spite of lumped simplifications the model allows to predict the mechanisms of creations of oscillations of the CM currents in a real system with a good accuracy.

Bearing current path and pulse rate in PWM-inverter-fed induction

In this paper, the authors present quantitative experimental results of the amplitude and rate of bearing current pulses emerging in common use PWM drives configurations. Based on measurement data and a simulation model, it has been shown that a whole path of bearing currents is closed inside of the motor and that these currents do not flow to a grounding arrangement as had been suggested in previous works.

AC/DC/DC Interfaces for V2G Applications—EMC Issues

Presented in this paper are the results of research connected with common mode (CM) interference generated by ac/dc/dc power electronic interfaces, which will very probably be commonly used in the future vehicle-to-grid systems. The results obtained show that the conducted CM interference generated by these converters in a low-voltage grid can be coupled to a medium-voltage (MV) network and observed at distant points under overhead MV lines. The developed passive CM voltage compensator dedicated for ac/dc/dc interfaces is recommended as an effective method for conducted interference reduction, preventing both aggregation and flow of interference in distant circuits.

Suppression of conducted EMI in four-quadrant AC drive system

This paper addresses problems connected with flow of conducted EMI on both sides of four-quadrant AC drive system. On the basis of measurements done in both time and frequency domains the passive methods of conducted EMI suppression have been proposed.

Time-Domain-Based Assessment of Data Transmission Error Probability in Smart Grids With Electromagnetic Interference

Reliable operation of the smart grid requires assurance of the electromagnetic compatibility of sensitive smart metering systems and power electronic converters, which introduce high-level electromagnetic interference. As it has been experimentally shown, currently available, normalized, and frequency domain tests are ineffective for the evaluation of data transmission error hazards. The mathematical time-domain model proposed in this paper enables assessment of the probability of errors occurring in a given transmission signal for known interference parameters. The validity of the model and its practical applicability have been experimentally verified.

Voltage harmonic distortion measurement issue in smart-grid distribution system

This paper presents the investigation results of voltage harmonic transfer accuracy problems through voltage transformers which are widely used in power quality monitoring systems in medium and high voltage grids. A simplified lumped parameters circuit model of the voltage transformer is presented and verified by simulation and experimental investigations. A number voltage transformers typically used in medium voltage grid has been tested in the conducted electromagnetic interference frequency range up to 30 MHz. The obtained results confirm that broadband voltage transfer function of the voltage transformer usually exhibits various irregularities which are primarily associated with voltage transformer winding parasitic capacitances.

Active and passive series compensation of common mode voltage in adjustable speed drive system

In This work the methods of active and passive series compensation of common mode (CM) voltage in the adjustable speed drive system have been compared. On this basis, the passive method is recommended for practical use due to its simplicity, cost-effectiveness and a lack of active elements. Also there have been presented merits of the series compensation in multilevel inverter drives.

Compensation of CM voltage in interfaces for LV distributed generation

In this paper the results of research connected with common mode (CM) interference generated by four-quadrant frequency converters and effective methods of CM voltage compensation will be presented. The results obtained show that conducted CM interference generated by these converters in a low voltage (LV) grid can be transferred by means of parasitic couplings into a medium voltage (MV) network and can be observed at distant points under overhead MV lines.

State of the art of active power electronic transformers for smart grids

The idea of power electronic transformer is known already over 20 years. There are numerous papers written about power electronic transformers. In the literature one can find tens on different topologies, control methods, standards, requirements etc. It is easy to loose insight what topology to use and where. In this paper a general overview of the power electronic transformer technology in terms of smart grids is presented. The information collected from the literature is classified and organized. In conclusion some generalizations are made and development trends are shown.

Series Passive Compensation of Common Mode Voltage in Multilevel Inverter Drives

This paper presents an approach to the problem of a magnetic saturation of CM chokes that accompanies the method of passive compensation of a common mode (CM) voltage in an inverter drive system. Measurements have been provided in a drive system including multilevel inverters and the filter having sinusoidal output voltages and zero CM voltage. The theoretical analysis and experimental results show that the problem with magnetic saturation becomes less important in multilevel inverter drives, thus permitting a reduction of size, weight and cost of inductive components of filters in such drives